Yet another Friday in Cairo's Tahrir Square turned into a day of bloodshed as protesters outraged by the killing of 74 soccer fans in a stadium riot on Tuesday, Jan. 31  for which they blame authorities  clashed with police.

Throughout Thursday night and Friday, protesters battling to reach the Ministry of the Interior skirmished with police, breaking down barricades and pushing forward through volleys of tear gas and rubber bullets. "It was like a war," said a young doctor who had spent the night working at one of at least five field hospitals set up in Tahrir to treat the wounded. He declined to give his name for fear of retribution from the police. "We didn't sleep at all," said another. "In just this tent, we had 500 people in eight hours. It started with tear gas, then wounds from stones. And after that it was shotgun pellets." Four people have died and more than 1,500 have been injured in major cities across the country since protests broke out on Thursday, according to the Associated Press. (PHOTOS: Egyptian Protests Continue After Deadly Soccer Riot)

The protests began after an incident in a soccer stadium in the coastal city of Port Said, where a riot broke out at the end of match, leaving 74 people dead  most of them fans of the popular Cairo team al-Ahly. Medical officials say most of the deaths resulted from a stampede toward the stadium's locked exits, as fans and players from al-Ahly surged in desperation to escape supporters of the home team, al-Masry, who attacked them with sticks and knives.

Stadium stampedes and fights between rival fans are not uncommon in the history of international soccer. But Egypt's disaster, in which police stood by and watched as fans fought and were trampled, stirred allegations of a conspiracy by the country's military rulers and the widely hated police force. The hardcore al-Ahly fans known as ultras have taken a leading role in the Tahrir Square rebellion over the past year, often serving among its front-line fighters in confrontations with the police. With postrevolutionary Egypt a tinderbox of frustration and anger, the Port Said deaths provided the spark that lit the most recent fire.

Young protesters, soccer ultras among them, have clashed repeatedly with Egyptian security forces in the year since President Hosni Mubarak was forced out by a popular uprising. Despite the dramatic events  Egypt completed its first truly democratic election for a new parliament in January  little else has changed in the lives of ordinary Egyptians. The faltering economy that had helped fuel last year's uprising has descended into crisis mode, leaving many Egyptians even more desperate than they were a year ago, while Mubarak's system of endemic corruption in every sector of public and private life has barely been budged. The military council to which he ceded power has drafted its own rules and continues to mete out harsh justice in closed military courts to thousands of dissenters, behavior that has prompted many to view the military as an obstacle to a democratic transition. And there's been little serious effort to hold accountable those authorities responsible for hundreds of deaths in the regime's attempts to to suppress the rebellion. (PHOTOS:
Police and Protesters Clash in Cairo)

"We came today to stop the bloodshed of Egyptians, to take down the military council and to have immediate presidential elections," said Ahmed Hamdi, a 28-year-old day laborer who joined the protest on Friday. The generals have said they would hand over executive authority to a President to be chosen in a vote expected before June 2012.

Others on the streets Friday said they wanted to see an end to corruption, justice for an abusive police force and better living conditions for themselves. "We demonstrate because of what happened to the youth, and they promised us certain things like stability, but we've been here for 13 months, and it hasn't happened," said protester Mona Mahmoud, 49.

On Friday, the start of the Egyptian weekend, thousands flooded into Tahrir Square after a night of clashes to voice their dissent or simply to watch. Some were soccer fans; many said the deaths in Port Said had spurred them to action. But the anger over the government's failure to prevent Tuesday's bloodshed and, more specifically, the police force's alleged collusion in the stadium violence, reignited broader grievances.

Indeed, the continued willingness of scores of young Egyptians to put their lives on the line in a battle that many beyond the square deem pointless  challenging the police force for control of the building that houses the Ministry to which it answers  speaks more to a widespread sense of frustration among Egypt's youth than to a unified and coherent goal.

By nightfall on Friday, the streets branching from Tahrir to the Interior Ministry still resounded with the cracks of tear-gas canisters and rocks hitting pavement. On Fahmy Street, which leads straight to the hulking pink Ministry building, young rebels continued to chant, hurling stones at the seemingly impenetrable fortress. Periodic volleys of tear gas rained down, one after the other, landing in their midst and turning the air white with choking gas and panicking the crowd of mostly young men (some of them children) into stampedes of coughing, shouting to retreat. Some fell to the ground and were trampled by others or choked on the gas. Swarms driven into side alleys searched for a way out. But once the gas cleared enough to breathe and the wounded were ferried away on the backs of motorcycles, the protesters invariably regrouped for a new assault. (MORE: The Brutal, Shadowy War for Hearts and Minds)

Some say their goal is to burn the Ministry to the ground. Others say the point is to send a message through perseverance. They know that this demonstration  like scores before it  is unlikely to bring down the military council or even win reforms in the police force, said Mohamed Adel, 20, as the men around him threw rocks. "But it's a way of mounting pressure," he said. "After 18 days of pressure, Mubarak left." For many Egyptians who watched last year's uprising topple a dictator after 30 years of stagnation, protest remains the only clear method of instigating change.

"It's not political goals," says Adel Radwan, a doctor working at one of Tahrir's field hospitals. "It's that they want to live as human beings." Most of the wounded he has treated in this fight as well as the ones before it are young men, he says. Some are poor. Others are educated and middle class. All are angry. Says Radwan: "They're asking for their freedom, to be treated as human beings and to have the minimum required to live."